After three damaging oil spills within ten days, environmentalists called for more accountability, especially from state-owned oil giant Petroleo Brasileiro (PETROBRAS). The latest rash of incidents followed a January spill from a broken PETROBRAS pipeline, which did extensive damage to the Guapimirim mangrove swamps in Guanabara Bay just north of Rio de Janeiro . In the most serious of the latest spills, a pipeline at the Getulio Vargas Refinery in Araucaria burst and dumped more than 4 million liters of crude oil into the Barigui River, a tributary of the Iguacu River, on July 16. Officials called the spill the country's worst such disaster in the last 25 years and the worst oil spill ever to occur on a river.